The PARTITION BY clause sets the range of records that will be used for each “GROUP” within the OVER clause. In your example SQL, DEPT_COUNT will return the number of employees within that department for every employee record. (It is as if you’re de-nomalising the emp table; you still return every record in the emp … Read more
The PARTITION BY clause sets the range of records that will be used for each “GROUP” within the OVER clause. In your example SQL, DEPT_COUNT will return the number of employees within that department for every employee record. (It is as if you’re de-nomalising the emp table; you still return every record in the emp … Read more
You can use mysqlcheck to do this at the command line. One database: mysqlcheck -o <db_schema_name> All databases: mysqlcheck -o –all-databases
There’s a caveat with the general 39 character IPv6 structure. For IPv4 mapped IPv6 addresses, the string can be longer (than 39 characters). An example to show this: IPv6 (39 characters) : ABCD:ABCD:ABCD:ABCD:ABCD:ABCD:ABCD:ABCD IPv4-mapped IPv6 (45 characters) : ABCD:ABCD:ABCD:ABCD:ABCD:ABCD:192.168.158.190 Note: the last 32-bits (that correspond to IPv4 address) can need up to 15 characters (as … Read more
Primary Key: There can only be one primary key constraint in a table In some DBMS it cannot be NULL – e.g. MySQL adds NOT NULL Primary Key is a unique key identifier of the record Unique Key: Can be more than one unique key in one table Unique key can have NULL values It … Read more
From what I’ve read, this error means that you’re not referencing the table name correctly. One common reason is that the table is defined with a mixed-case spelling, and you’re trying to query it with all lower-case. In other words, the following fails: CREATE TABLE “SF_Bands” ( … ); SELECT * FROM sf_bands; — ERROR! … Read more
It seems the answer to your question is no, however one hack you can use is to assign a dummy column to separate each new table. This works especially well if you’re looping through a result set for a list of columns in a scripting language such as Python or PHP. SELECT ” as table1_dummy, … Read more
PostgreSQL does not define round(double precision, integer). For reasons @Mike Sherrill ‘Cat Recall’ explains in the comments, the version of round that takes a precision is only available for numeric. regress=> SELECT round( float8 ‘3.1415927’, 2 ); ERROR: function round(double precision, integer) does not exist regress=> \df *round* List of functions Schema | Name | … Read more
Since PostgreSQL 8.2 you have to use: GRANT USAGE, SELECT ON SEQUENCE cities_id_seq TO www; GRANT USAGE – For sequences, this privilege allows the use of the currval and nextval functions. Also as pointed out by @epic_fil in the comments you can grant permissions to all the sequences in the schema with: GRANT USAGE, SELECT … Read more
It’s better to use either of the following: — Method 1. SELECT 1 FROM table_name WHERE unique_key = value; — Method 2. SELECT COUNT(1) FROM table_name WHERE unique_key = value; The first alternative should give you no result or one result, the second count should be zero or one. How old is the documentation you’re … Read more